The present invention relates to computer networks in general, and more particularly relates to methods and apparatus for adjusting the local service policy within an ATM switch based on non-ATM protocol service parameters.
The increasing importance of Asynchronous Transfer Mode (ATM) network technologies and protocols has spawned efforts to allow non-ATM-based network applications and protocols to communicate via ATM networks. Two such efforts include the LAN Emulation (LANE) specification and the Multi-Protocol Over ATM (MPOA) specification, both of which allow non-ATM protocol data units (PDU), such as Ethernet frames and Internet Protocol (IP) packets that have been reformatted into ATM PDUs by the ATM Adaptation Layer (AAL), to be transmitted between non-ATM networks via an ATM network.
FIG. 1 is a simplified conceptual diagram of a prior art illustration of two non-ATM networks 10 and 12 communicating via an ATM network 14. Two ATM edge devices 16 and 18 are shown interfacing with a plurality of non-ATM endpoints, such as 20 and 22, and two ATM switches 24 and 26. A non-ATM PDU 28 sent by endpoint 20 and destined for endpoint 22 is received at edge device 16. Edge device 16 establishes a data direct virtual channel connection (VCC) 30 with edge device 18 via switches 24 and 26 in accordance protocols such as LANE or MPOA. Edge device 16 then reformats the non-ATM PDU 28 into ATM PDUs 32 at its AAL and transmits the ATM PDUs 32 via data direct VCC 30 to edge device 18 where they are reassembled into the non-ATM PDU 28 and transmitted to endpoint 22.
In accordance with the prior art an ATM endpoint typically establishes a xe2x80x9ccontractxe2x80x9d specifying bandwidth and other quality of service (QoS) requirements when establishing a VCC. Once the VCC has been established, the contract is not renegotiated, and each ATM switch along the VCC must provide service within the boundaries set by the QoS contract. A switch""s xe2x80x9clocal service policyxe2x80x9d (LSP) as defined herein refers to the set of rules and mechanisms that a switch uses to service incoming and outgoing cells within these boundaries. The LSP determines, for example, the order in which the cell queues are emptied, weights for the buffers, and when to drop cells. While the LSP must always fulfill the QoS contract, the LSP may be dynamically changed to accommodate transient states as long as the overall QoS contract is maintained. Since multiple sources of non-ATM PDU data may share the same VCC, the bandwidth and QoS requested by edge device 18 and established for VCC 30 might be suitable for one type of non-ATM PDU data but not for another type of data since edge device 18 may be required to support several non-ATM PDUs, each representing a different type of data being communicated. This is true where a separate VCC is established to support a single non-ATM protocol, referred to as a non-multiplexed VCC, and especially true where a single VCC supports two or more non-ATM protocols, referred to as a link layer multiplexed (LCC) VCC.
The following publication is believed to be descriptive of the current state of the art of ATM technology and terms related thereto:
Kwok, T., xe2x80x9cATM: The New Paradigm for Internet, Intranet, and Residential Broadband Services and Applications,xe2x80x9d Prentice Hall, 1998.
The disclosures of all patents, patent applications, and other publications mentioned in this specification and of the patents, patent applications, and other publications cited therein are incorporated herein by reference in their entirety.
The present invention provides methods and apparatus for adjusting the local service policy within an ATM switch based on non-ATM protocol service parameters subsequent to a VCC being established.
There is thus provided in accordance with a preferred embodiment of the present invention a method for adjusting an ATM switch local service policy based on a non-ATM protocol service parameter, the method including the steps of a) inspecting the payload of an ATM PDU received at a switch along at least one VCC to identify a non-ATM PDU protocol identifier included in the payload, b) inspecting the payload to identify a non-ATM PDU service identifier associated with the non-ATM PDU protocol identifier, and c) selectively adjusting a local service policy attribute within the switch for the at least one VCC based on the non-ATM PDU service identifier in accordance with an adjustment value in predefined association with the non-ATM PDU protocol identifier and the non-ATM PDU service identifier.
Further in accordance with a preferred embodiment of the present invention the ATM PDU is an AAL PDU.
Still further in accordance with a preferred embodiment of the present invention the method further includes the step of d) identifying a first cell in the AAL PDU and thereafter performing steps a)-c).
Additionally in accordance with a preferred embodiment of the present invention the steps a)-d) are performed for at least two non-ATM PDUs on the VCC, tie non-ATM PDUs are of different protocol types.
Moreover in accordance with a preferred embodiment of the present invention the at least one VCC includes at least two VCCs, and the steps a)-d) are performed for at least one non-ATM PDU on each of the at least two VCCs.
Further in accordance with a preferred embodiment of the present invention the AAL PDU is of an AAL type selected from the group consisting of: type 1, type 2, type 3/4, and type.
Still further in accordance with a preferred embodiment of the present invention the method further includes maintaining a predefined association between a specific non-ATM PDU protocol identifier and the position of the non-ATM PDU service identifier in the payload.
There is also provided in accordance with a preferred embodiment of the present invention apparatus for adjusting an ATM switch local service policy based on a non-ATM protocol service parameter including means for inspecting the payload of an ATM PDU received at a switch along at least one VCC to identify a non-ATM PDU protocol identifier included in the payload, means for inspecting the payload to identify a non-ATM PDU service identifier associated with the non-ATM PDU protocol identifier, and means for selectively adjusting a local service policy attribute within the switch for the at least one VCC based on the non-ATM PDU service identifier in accordance with an adjustment value in predefined association with the non-ATM PDU protocol identifier and the non-ATM PDU service identifier.
Further in accordance with a preferred embodiment of the present invention the ATM PDU is an AAL PDU.
Still further in accordance with a preferred embodiment of the present invention the apparatus further includes means for identifying a first cell in the AAL PDU.
Additionally in accordance with a preferred embodiment of the present invention any of the means are adapted for use with at least two non-ATM PDUs on the VCC, the non-ATM PDUs are of different protocol types.
Moreover in accordance with a preferred embodiment of the present invention the at least one VCC includes at least two VCCs, and any of the means are adapted for use with at least one non-ATM PDU on each of the at least two VCCs.
Further in accordance with a preferred embodiment of the present invention the AAL PDU is of an AAL type selected from the group consisting of: type 1, type 2, type 3/4, and type.
Still further in accordance with a preferred embodiment of the present invention the apparatus further includes maintaining a predefined association between a specific non-ATM PDU protocol identifier and the position o the non-ATM PDU service identifier in the payload.